Problem Note 36073: ADJUST=DUNNETT DIFF=CONTROL multiple comparisons may not converge in PROC LIFETEST
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The ADJUST=DUNNETT DIFF=CONTROL(...) pairwise comparisons may not converge when used in a k-sample tests scenario on the STRATA statement (when the GROUP= option is NOT specified). A WARNING message is written to the log and the adjusted pvalues are reported as missing values. This problem affects all k-sample tests such as the logrank, Wilcoxon, Tarone, Peto, ModPeto, Fleming and LR tests.
Currently, a WARNING message is written to the log:
WARNING: The ADJUST=DUNNETT p-values and confidence limits
cannot be computed because the Dunnett-Hsu
approximation did not converge. Try
ADJUST=SIMULATE.
The Dunnett-Hsu approximation depends on an iterative algorithm to approximate the covariance matrix. In the k-sample tests scenario, the covariance matrix is singular, which causes problems with the iterative algorithm.
To circumvent the problem, use ADJUST=SIMULATE.
Operating System and Release Information
| Product Family | Product | System | SAS Release | |
| Reported | Fixed* | |||
| SAS System | SAS/STAT | z/OS | 9.2 TS1M0 | 9.2 TS2M2 |
| Microsoft® Windows® for 64-Bit Itanium-based Systems | 9.2 TS1M0 | 9.2 TS2M2 | ||
| Microsoft Windows Server 2003 Datacenter 64-bit Edition | 9.2 TS1M0 | 9.2 TS2M2 | ||
| Microsoft Windows Server 2003 Enterprise 64-bit Edition | 9.2 TS1M0 | 9.2 TS2M2 | ||
| Microsoft Windows XP 64-bit Edition | 9.2 TS1M0 | 9.2 TS2M2 | ||
| Microsoft® Windows® for x64 | 9.2 TS1M0 | 9.2 TS2M2 | ||
| Microsoft Windows Server 2003 Datacenter Edition | 9.2 TS1M0 | 9.2 TS2M2 | ||
| Microsoft Windows Server 2003 Enterprise Edition | 9.2 TS1M0 | 9.2 TS2M2 | ||
| Microsoft Windows Server 2003 Standard Edition | 9.2 TS1M0 | 9.2 TS2M2 | ||
| Microsoft Windows XP Professional | 9.2 TS1M0 | 9.2 TS2M2 | ||
| Windows Vista | 9.2 TS1M0 | 9.2 TS2M2 | ||
| 64-bit Enabled AIX | 9.2 TS1M0 | 9.2 TS2M2 | ||
| 64-bit Enabled HP-UX | 9.2 TS1M0 | 9.2 TS2M2 | ||
| 64-bit Enabled Solaris | 9.2 TS1M0 | 9.2 TS2M2 | ||
| HP-UX IPF | 9.2 TS1M0 | 9.2 TS2M2 | ||
| Linux | 9.2 TS1M0 | 9.2 TS2M2 | ||
| Linux for x64 | 9.2 TS1M0 | 9.2 TS2M2 | ||
| OpenVMS on HP Integrity | 9.2 TS1M0 | 9.2 TS2M2 | ||
| Solaris for x64 | 9.2 TS1M0 | 9.2 TS2M2 | ||
ADJUST=DUNNETT DIFF=CONTROL multiple comparisons may not converge in PROC LIFETEST for the k-sample tests scenario (STRATA statement without the GROUP= option)
| Type: | Problem Note |
| Priority: | medium |
| Topic: | Analytics ==> Survival Analysis SAS Reference ==> Procedures ==> LIFETEST |
| Date Modified: | 2009-05-28 13:51:13 |
| Date Created: | 2009-05-27 20:20:31 |